title: Zirconia abutments for single-tooth implant restorations: a retrospective and clinical follow-up study.
abstract: OBJECTIVE
  To evaluate the clinical outcome of custom-made zirconia abutments for implant-supported single-tooth restorations up to 5 years after insertion.
  
  
  METHODS
  The study comprises two parts: (Part 1) retrospective evaluation of records of 130 patients treated with 185 single-tooth implant restorations using zirconia abutments; (Part 2) clinical examination of 25 patients with 40 restorations placed >3 years ago. Oral surgeons placed the implants. The prosthodontic treatment was provided at a prosthodontic specialist clinic. The restoration was either an all-ceramic crown for cementation or a screw-retained one-piece restoration with the veneering porcelain baked directly to the zirconia abutment. Registration of all patients' records comprised clinical and radiographic data from insertion of the restoration up to the last visit at the clinic.
  
  
  RESULTS
  Parts 1 and 2: The zirconia abutments performed well over the follow-up period. The rates of both technical and biological complications were low, and the patients were in general extremely satisfied with the restorations. No all-ceramic crowns fractured during the observation period. Two abutments (1%) fractured, one at insertion, the other after 2 months. Part 2: There were no significant differences for changes in any of the soft tissue registrations or the peri-implant marginal bone level between the conventional two-piece abutment-crown restoration and the one-piece restoration. The peri-implant bone level changes from placement to the clinical examination 3-5 years later were small (mean 0.29 mm, SD 0.87 mm).
  
  
  CONCLUSIONS
  Zirconia abutments for single-implant crowns seem to demonstrate good short-term technical and biological results.
authors.affiliation: Department of Prosthetic Dentistry and Oral Function, Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Oslo, Norway. anders.ekfeldt@odont.uio.no
authors.forename: Anders
authors.initials: A
authors.lastname: Ekfeldt
authors.forename: Björn
authors.initials: B
authors.lastname: Fürst
authors.forename: Gunnar E
authors.initials: GE
authors.lastname: Carlsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000539:Alveolar Process / Q000473:pathology; D002484:Cementation / Q000379:methods; D003442:Crowns; D000044:Dental Abutments; D003738:Dental Cements / Q000737:chemistry; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous; D019250:Dental Implants, Single-Tooth; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D003801:Dental Veneers; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057893:Immediate Dental Implant Loading; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003738:Dental Cements; D003764:Dental Materials; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide